Starch-caustic in apatite-ilmenite froth flotation



.April 12, 1949.

L. L. MCMURRAY STARCH-CAUSTIC IN APATITE-ILMENITE FROTH FLOTATION Filed Dec. 20, 1945 ATTORN EY Patented Apr. 12, 1949 STARCH- CAUSTIC IN. `APATITE--ILMENITE FROTH FLOTATION Lynn L. McMurray, Asheville, N. C., assigner to American Cyanamld Company,

a corporation of Maine Applicationy December 20, 1945, Serial No. 636,227

This invention froth notation of those metallic oxide ores containing excessive amounts of phosphate minerals. More particularly, it is concerned with the separation of phosphorous-bearing minerals such as apatite from metallic oxide minerals such as ilmenite, rutile, magnetite, hematite and the like.

The typical problems involved as well as their solutions are found in the production of ilmenite concentrates. In commercial practice, theuse of titanium oxides has become increasingly important and accordingly the demand for high grade ore from which they may be recovered has steadily increased. Unfortunately, While there are many natural deposits of titanium minerals, the grade of these ores in many cases is not sufficiently high to make recovery of titanium oxides therefrom commercially feasible. Particularly is this true of most deposits within the United States. Therefore, while the process is not limited thereto, the invention will'be illustrated by its application to titanium ores and ilmenite in particular.

Natural deposits of titanium-bearing minerals are usually ores containing, in addition to the titanium-bearing mineral such as ilmenite, rutile or the like, a Silica-bearing gangue. Ordinarily, this silica and/or silicate content must be reduced to produce a concentrate meeting commercial standards, for example, to be used as raw material for the production of titanium oxide pigments.

Moreover, a problem with whichthe present invention is particularly concerned is presented by the fact that in addition to the silica or silicates, many ores, States, contain a certain amount of phosphorousbearing minerals. In the illustrative case of ilmenite, this is frequently apatite. The presence of phosphorus is objectionable in a raw material for the production of titanium oxide pigments relates to the bcneiiciation by' particularly in the Unitedv Claims. (Cl. 209-167) in their various crystal forms such as rutile or anatase. Particularly is this true in the latter case. A commercially acceptable concentrate must have a low P205 content. Since thePzO5 assay may vary from about 1-2 in ilmenite concentrates obtained from ores which are worked primarily for other constituents to 12% or more, as 'found in ilmenite ores such as nelsonite, the reduction of the P205 content is essential. Those New York, N. Y.,

2 processes which in the past have been employed to reduce the silica or silicate content are not ef-I fcctive for this purpose.

Despite the demand therefor, there has been available no process for readily and effectivelyproducing concentrates of metallic oxides such as ilmenite or the like, suniciently low in P205 content. Neither have the concentrates previouslyobtainable always been in a satisfactory physical condition in which they can be readily dewatered and dried for further processing.

It is, therefore, a pr ncipal object of the present invention to provide a process bywhich a A concentrate satisfactorily low in S102 and P205 content can be obtained. It is also an object to provide a process whereby this is accomplished in an economical manner and with good recovery. It is a further object to provide suitable reagents for use in this process, which reagents are simple in use, readily obtainable and effective in operation.

It is with the reduction in the P205 assay that the present invention is primarily concerned. Its practice, however, also effectively reduces the S102 assay in the iinal metallic oxide concentrate. In accordance with the present invention separation of apatite, for example, from a metallic oxide such as ilmenite, is made by preparing a deslimed feed, conditioning it with a novel depressant for the ilmenite and siliceous content, floating off the bulk of the apatite, repeating the flotation if the P205 is not suiiciently reduced, removing any residual depressant, and taking the ilmenite concentrate from the residual solids by means of a similar type of promoter used for the apatite.

The invention Will be discussed in conjunction with the accompanying drawing which delineates a typical flow scheme of a process involving the practice of the present invention.

In discussing flow scheme, and details of the present invention elsewhere throughout the speciicati-on, the separation of apatite a commonly-occurring phosphate, from ilmenite FeO.TiO2 a typical metallic oxide, is described. However, the present invention is not to be construed as being limited to the separation of the 3 two latter mentioned minerals. but covers broadly the separation of phosphorous-bearing minerals from metallic oxides.

It is highly desirable that the selective apatite iloat be carried out with anionic-type reagents, if possible, since the latter not only are both simpler and more economical in use but produce av Referring to the flow sheet it will be seen that y the initial operations are conlerned with preparing the ore. As shown in the drawing, this comprises grinding or otherwise reducing the ore to a suitable size for otation, and removing the slimes. Any combination of crushing. grinding, and desliming steps may be used. In the case of many ores, it has been found to be good practice to crush the' whole ore to about minus 10 mesh and then remove the primary sllmes. This permits discarding a substantial portion of the original weight, usually with a Very small loss of ilmenite. 'It is the deslimed material which forms the feed to the grinding circuit shown in the accompanying iiow sheet. As shown, the feed is usuallyground to less than minus l mesh and preferably to minus 50 or minus 60 mesh. Grinding is followed by a secondary desliming operation producing a deslimed product in suitable condition for further processing.

The deslimed sands are conditioned with the ilmenite depressants and the apatite promoter; This conditioning step is carried out at high solids although it may be done at flotation density if so desired. The ilmenite depressant may be referred to as caustic starch although the designation is a slight misnomer. The reagent actually comprises a mixture of an alkali such as sodium hydroxide and starch. Preferably it is fed as a solution containing about 5-10% dissolved solids. The alkali-starch ratio may vary from as little as about 5-1 to as high as about 30-1.

It has been found that good results are obtained for most purposes using about 20 parts of caustic per part of starch. A suiiicient amount should be used to produce depression of the ilmenite and to produce a pH of at least about 8.0-8.5 at flotation density, the solution being added and conditionedwith the pulp for suicient time to insure thorough dissemination.

At the same time the anionic promoter for the at least about 8.0-8.5. The alkali apatite is added. It has been found that this may be substantially any good anionic promoter of the fatty-acid nr soap type. Good results are obtained with Ifatty acids such as oleic acid, shoil fatty acids, cocoanut-oil fatty acids and the like; with resin or naphthenic acids, talloel and the like. These may be used -per se or as sodium. potassium or ammonium soaps thereof. Sulfonated reagents such as sulfonated or sulfated higher aliphatic alcohols; sulfonated fatty acids and fatty-acid-glyceride oils; sulfonated petroleum hydrocarbons of the mahogany and green types and the like may also be used ."end liquor,"

tions. In some few cases more may be required.v

Excessive amounts over that necessary to concentrate the apatite should be avoided as tending to overcome the eil'ect of the ilmenite depressant. It appears to make little difference whether the talloel is added per se or in a presaponied lform since there is enough alkali present to assure saponification in situ during conditioning.

After conditioning, the pulp is subjected to otatlon. If conditioning was at lhigh solids the pulp is flrst reduced to flotation density of from 15-20% solids. Flotationis carried out until the apatite removal is apparently complete. This initial flotation operation will be found to iioat and concentrate the major portion of the apatite content in the feed. In some cass, the apatite removal ls suiilciently complete. The residual apatite content of the initial flotation tailing may be too high to meet specifications for a good ilmenite concentrate. Therefore, as shown in the drawing, the conditioning and otation procedures are usually advantageously repeated taking off a second apatite concentrate or middling product and leaving a tailing of satisfactorilylow P205 content.

These apatite concentrates may be treated in any suitable manner. As shown in the drawing, the apatite concentrates are combined and subjected to a cleaner land recleaner otation, the tailings from which are recycled to the grinding step but may be discarded if so desired. The resultant product is a clean, saleable, apatite concentrate.

To obtain the nal ilmenite concentrate, the machine discharge or tailing, from the apatite concentrating is treated to remove any residual depressant, conditioned with an ilmenite promoter and a pulp-conditioning agent. As shown in the drawing, the residual depressant may be simply washed out ofthe apatite tailings before further treatment of the latter. However, as shown, it is preferable that the tailings be given an acid washing before the ilmenite iiotation. The pulp-conditioning agent may be either an alkali or an acid. When an alkali is used it is added in a sufiicient amount to produce a pH of usually employed is caustic soda, but if the occasion warrants, it may be substituted by potassium or ammonium hydroxide. The use of caustic alkali is probably the most conventional, because of its greater availability and lower cest.

In using acid as the pulp-conditioner it has been found that it is possible in some cases to reduce the SiO: assay of the ilmenite concentrate somewhat. The inorganic sulfuric acid. However, acetic acid also has been this it is apparent that not critical. Where the ilmenite concentration is being carried out in conjunction with the manufacture of titanium pigments, so-called comprising about 20% sulfuric acid acid usually used is the nature of the acid isv 1 and 10% FeSO4, is usually available. 'I'liismay' be used. The amounts required are smailas compared with the usual amount of alkali used. be-

ing generally in the neighborhood of=0.10.5 lb.

of H2804 or the equivalent. per ton of feed. The

amount used in this way is small enough so that its eiect is probably one of activating the ilmenite somewhat rather than a scrubbing or cleaning.

The promoter used may be the same or a diierent anionic reagenti. from that used in concentrating apatite. Again talloel is perhaps the preferred reagent. It is saponiiication would be useless in the presence of acid although it will occur in situ when alkali is used.

Asshown in the drawing, the acid treatment is preferably carried out as a separate step. From about 5 to 10 lbs. of acid per ton of feed is usually found adequate. After thoroughly agitating the pulp-acid mixture, it is dewatered and washed thoroughly. Two or three washings are used to remove substantially all the excess acid. This washed pulp is then used as feed in the ilmenite flotation. In using this special acid washing step it is possible to leave a trace of acid in the pulp and simply condition with it the promoter for the ilmenite thus simply providing an acid source if the ilmeniteotation. is to be done in acid circuit. On the other hand, it is perhaps preferable to use an alkaline circuit for the ilmenite flotation. The acid is washed out quite completely.

As shown in the drawing. whether the acid or alkali treatment is used, the pulp which has been reconditioned is fed to the ilmenite flotation circuit and an ilmenite concentrate removed. This rougher concentrate is usually given one by refiotation, and preferably at least another additional cleaning. The tailings from the i1menite cleaner and recleaner flotation operations may be discarded if so desired. Usually at least the recleaner tailing may be advantageously recycled to the grinding operation.

The invention will be further illustrated in conjunction with the following examples which are intended as'illustrative only. All parts are by weight unless otherwise noted. The ore treated in the following examples was a nelsonite ore containing in addition to ilmenite. rutile,` magnetite. and hematite, apatite and siliceous gangue minerals. Before the treatmentshown in the following examples vthe ore had been reduced to minus mesh and hydraulically deslimed.

EXAMPLE 1 In order to show the effectiveness of the starchcaustic as an ilmenite depressant. a sample of the ore was ground to minus 65 mesh and deslimed, the slimes being discarded. Sands as a thick pulp were conditioned for 1% minutes with the reagents designated group I, in Table Iv and an apatite concentrate (No. 1) floated for 6 minutes. This first apatite concentrate was cleaned, once, the cleaner tailing being designated "Midd in Table I. The tailings from this initial flotation operation were dewatered to a thick pulp and conditioned again for 1% minutes with the reagents designated "group II" and a second apatite concentrate (No. 2) was iloated. The tailings from the second apatite notation were washed and dewatered, conditioned for 1% minutes with the reagents designated group III and an ilmenite rougher concentrate Iremoved for about 6 minutes. The ilmenite rougher concentrate was cleaned three times,

generally added per se since precleaning lb./ton. The results the various cleaner .tailings being-combined and Adesignated filmenite middlings asshowninI-ableL The reagents` used and the metallurgical results are shown inthe following 'liable I.

Table! t R yt Reagent GroupI Group Il ilroup III \y.-y;.\ v v e.o\ 1.o asc Los Assay Recovery Product I'og:

not T10, no. frio,

parlarmi am 34.0 5.4 83.5 3.9 .fatite No. 2.. r4.0 4.4 15.0 2. l. 2. l me@ 5.a 14.0 1an n.1 3.5 40.2 0.11 45.9 0.5 64.3 .zas ooo zas 2.7 22.4 n o o an iai o1 3.a mamme.) mao 5.50 51.2 100.0 100.0

Another sample of the ore was treated in the same way as in Example l, except that the two apatlte concentrates were combined .and cleaned twice to produce a final apatite concentrate, the cleaner tailings being combined and designated apatite Midds l and 2 in Table-II.' vAlso, the ilmenite rougher concentrate was cleaned only twice, the combined cleaner tailings being designated ilmenite Midds 1 and 2 as shown in Table II. The reagents and results following Table II.

Table It Reagent Reagent Reagent Group I Group Il Group III Analysii Reooverty Per cent D p Muet weight P305 T103 P205 Tio;

Apatite Conc 16.8 as. a 2.1 a5. 5 1. 2 Aponte Mldds. i andz 11. 5 7. e 12. 5 11. 4 4, s llmenite Concl 57.9 c. 2 44. s 1. 3 s1. 3 llmenitelvildds 1 and2 8.2 1. i 2o. 2 1. 2 5. o Final 'railing 5. e o. 9 o. 1 o. o 1. 1 Feed (Cale.) 100.0 7. 5 29. 7 10o. o 100. o

1 sieg-1.24% analysis.

Exam/21.: 3

In order to illustrate the benecial effect of an acid wash in reducing the silica content of the ilmenite concentrate, Example 2 was repeated exactly except that the illnenite flotation feed was conditioned for 5 minutes with l0 lbs/ton of 98% H2804 and the sands were washed twice. To overcome any residual acid, the caustic content of the reagent group 3 was raised to 1.0 are shown in the following TableIlI.

arel shown inthe v the sodium, potassium 1 slof-0.62 analysis.

Examnn 4 In order to illustrate .the eiect of carrying out the ilmenite dotation in the presence" of acid, Example 2 was repeated except that in reagent group 3 sulfuric acid (98%) was used instead of caustia The reagentiA quantities and illustrative results `are shown in the following Table IV.

Tabzerv R ent ent Reagent Gp I riap II Group III I fnal-y'sis Begoverty Pert iper cent per den Produ weight r' P205' T10: P205 "I .TOz

patire conc 14. 0 :ia-e 1. e as. 9 ma Apatlte Mdds. l and?. 11. 3 6. 0 20. 3 10. 2 7:6' llmenite Conc.l 51. 0 0. 14 45. 8A L ll 77. llmenite Midds. l and 2 17. 1 0. 8 26. 4 2. l 13. l silicate Gangne 5. 7 `0.1% 4. 0 0. 7 0. 8 Feed (Calc.) 100. 0 -6.6 29. 9 100.0 100.0

l slof-0.84% analysis.

I claim:

1. A method of separating phosphorous-bearlng minerals from mixtures thereof containing at least one metallic --oxide mineral which' comprises the steps of subjecting an aqueous-pulp of the mixture to froth otation in the presence of starch and a member of the group consisting of.

and ammonium hydroxides the starch-alkali ratio ranging from 1:5 up to-1:30 and a sumcient amount being used to produce a pH of at least 8 and to effectively -depress substantially all-of the metallic oxide-min- `eral content and a -'suiicient amount of an milonic-type promoter selected from the longchain fatty acid, resin acid, naphthenie vacidj `types, talloel,V their soluble soaps and mixtures' thereof to oat'selectively the major portion of the phosphorous-bearing minerals.

. 2. A method of separating apatit'e from mixtures thereof containing at least one metallic oxide mineral which comprises the steps of sub- .iectingan aqueous pulp of the mixture to. froth flotation in the presence of starch and a member` of the group consisting of-- the sodium, potassium. and ammonium hydroxides 'the'starch-lalkali ratio ranging from 1:5 up to 1:30 and aisuilicient amount being used to produce aspH ofat least B andto effectively depress substantially. all of the metallic oxidemineral content and'asuillcient amount 'of Ian. v:armonie-time :promoter selected from the long-chain fatty acid, resin acidg--naphthenic acid typesftalloel, their soluble soaps and mixtures thereof to iloat selectively the major portion of the apatite.

3.A method or. separating phosphorous-bearingminerals frommixtures thereof containing at' least onetitaniumbearing oxide mineral which comprises the steps of subjecting an aqueous pulp of the. mixture to froth fioation in the presence ofstarch and a'member of the group censistingy of the sodium, potassium and ammonium hydroxides the starch-alkali ratio ranging 'from 1:.5; up -to- 1 :30 and a suiiicient amount being used to produce a pH of at least 8 and to effectively depress substantially all of the titaniumbearing oxide mineral content and a sucient amount of an 4amonio-type. promoter selected from the long-chain fattyacid, resin acid, naphthenic acid types, talloel, their soluble soaps and mixtures thereof to float selectively the maior portion of the phosphorous-bearing minerals.

- 4. A method offseparating apatite from mixtures thereof containing at least one titaniumbearingoxide mineral which comprises the steps of subjecting an aqueous pulp of the mixture to frothilotation 4in the presence of starch and a member-of the group-consisting of the sodium, potassium and ammonium hydroxides the starchalkali ratio ranging from 1:5 up to 1:30 and a sumcient amount being used to produce a pH of at least 8. and to effectively depress substantially all ofthe titaniumbearing oxide mineral content and asuiiicient amount of. an anionic-type promoter. selected from the vlong-chain fatty acid, resin ..acid, naphthenic acid types, talloel, their soluble soaps and-mixtures thereof to float selectively the maiorportion of the epatite,

5. A process according to claim 1 in which-the alkali and -starch are fedV as an aqueous uid solution thereof, this solution being added to the gueo'uspulp and Aagitated therewith before the pulp is subjected to froth dotation.'

6.l A method of separating phosphorous-bearing minerals from mixtures thereof containing at least one metallic oxide mineral which comprises the steps of subjecting an aqueous pulp of the mixture-.to froth flotation .in the presence of starch and a member of the group consisting of the sodium, .potassium and ammonium hydroxides the starch-alkali ratio ranging from 1:5 up to 1;:30 andj; a suflicient amount being used to produce a pH of at least A'S and to 'effectively depress" all Aofthe metallic oxide mineral a sumcient amount of an anionictype promoter selected .from the long-chain fatty acid, resin acid, naphthenic'acid types, talloel, their soluble soapsan'd mixtures thereof to oat selectively the ni'ajor portion of the phosphorousbearing minerals, subjecting the tailing there-v troni toa'l second froth 'flotation operation with the same reagent combination, whereby substantiauyan' the 1 residual 'phosphorous-bearing mintrals are removed therefrom.

.7. A. metho'd of' -'separating tures thereof with titanium-bearing oxide minerals and silica-bearing gangue, which comprises thefsteps of making an aqueouspulp of the mixture; removing substantially all of the apatite from the' pulp, by conditioning the pulp with causticized starch and an amonio-type promoter for'the apatte.' selected I acid; resin? acid.. naphthenic acid types, talloel,

their ,soluble soaps and mixtures thereof, subjectyingthe conditioned 'pulp to froth flotation, collectfng'tnefrotn fconce'ntrate which floats and removing"-the4 'collected froth concentrate from 'epatite from mix! from the long-chain fatty'l the circuit; washing the residualI causticized starch from the residual solids; conditioning the latter with an anionic-type promoter for the titanium-bearing oxide mineral, selected from the noted promoters for apatite, and subjecting the pulp to froth dotation, whereby a titanium-bearing concentrate having a silica to be commercially acceptable is obtained.

8. A process according to claim 7 -in which the titanium-bearing oxide mineral flotation is carried out in the presence of a small amount of free strong acid.

9. A process according to claim '7 in vwhich the titanium-bearing oxide mineral otation is carried out in the presence of suiiicient alkali produce an alkaline pH.

assay low enough to u 1,914,695

from before being conditioned with the titaniumbearing oxide mineral promoter.

LYNN L. McMURRAY.

' REFERENCES CITED The following lreferences arerof record in the l file of this patent: l

k UNITED STATES PATENTS Number Name Date y, Lange June 20, 1933 2,288,497 JuneZO, 1942 Tartaron the apatite notation are 

